In many types of rolling-element bearings, the preload represents a significant operating parameter. The preload, which may also referred to as the “bearing preload,” influences wear and thus the service life of a particular rolling-element bearing. If, for example, a rolling-element bearing is subjected to a high dynamic or static load, it may be advisable to set a higher preload value than with lesser loads, in order to make possible as uniform as possible a distribution of the particular load on all rolling elements. Here the wear can occur, for example, due to the sliding component of the movement of the rolling elements along the respective berating rings. In particular at lower rotational speeds, a state of mixed friction can act in a wear-promoting and thus service-life-reducing manner.
On the other hand, using too large a preload can lead to an increase of the friction in an interior of the rolling-element bearing, which in turn can increase energy consumption.
Thus, while in the past there was a tendency for large preload values to be chosen more often in the interest of prolonging service life, recently the preload and its optimal setting have returned to the center of attention, not least because of the friction problem described above.
The setting of the preload in tapered roller bearings and angular contact ball bearings, but also in other bearings, remains, as in the past, a costly and imprecise process. The preload is conventionally set by either measuring a friction torque of the bearing assembly or by adjusting/setting the friction torque using a shim ring/fitting washer. In the first-mentioned friction torque setting, a friction torque increase is measured which is typically accompanied by an increase in the bearing preload. Once the bearing preload reaches a certain value, then, for example, nuts used for attaching the bearing or for generating the preload are secured against further turning.
The other method consists of measuring the components in the load circuit in question and then generating the required load path using a shim ring. This then induces (brings about) the required preload when the nut used for attaching and for generating the preload is tightened. In this case, based on the achieved tolerances of the components included in the load circuit in question, a shim ring is thus fitted/adapted such that on the one hand the position, and on the other hand the preload generated by the tightening of the nut, are harmonized/coordinated with one another. The conventional assembly method of such a rolling-element bearing, wherein the bearing preload represents a relevant parameter for the later use of the rolling-element bearing, can therefore often be wasteful, imprecise, and/or expensive.
There is therefore a need to for an easier way of determining a bearing preload of a rolling-element bearing.